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05-11-2021
01:09 PM

05-11-2021
01:09 PM

I have the following equations and i am trying to ge the values for b2 and D2.

I have all the other necessary values but i cannot get to solve this.

Have i mistyped the root equation?

I tried with the find function too.

Solved! Go to Solution.

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1 ACCEPTED SOLUTION

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05-11-2021
01:51 PM

05-11-2021
01:51 PM

Some errors:

1. You've type rectangular brackets here:

(around the theta function). Don't ever do that unless you want to create a matrix.

2. Your equations are NOT unit balanced with the given guess values for b2 and D2, set them to be 1 m each to correct that.

3. The root function can solve only ONE variable, not two, and not an expression (like b2/D2)...

In this case you can pull a trick to solve it with root anyway: Multiply the first equation on both sides with D2^2, then the left hand segment becomes equal to the right-hand segment of the second, and we can solve for D2:

Now we know D2, we can solve b2 with:

Or you can look up how to use a solve block in Prime poperly, and use that.

Or you can solve the set symbolically, like I showed in my first reply.

Success!

Luc

4 REPLIES 4

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05-11-2021
01:27 PM

05-11-2021
01:27 PM

Re: Help regarding root function or find function

Please attach the Prime worksheet, not just a picture.

Success!

Luc

Apart from that, there appear to be two possible solutions:

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05-11-2021
01:29 PM

05-11-2021
01:29 PM

Re: Help regarding root function or find function

Hello,

Here is the requested file.

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05-11-2021
01:51 PM

05-11-2021
01:51 PM

Some errors:

1. You've type rectangular brackets here:

(around the theta function). Don't ever do that unless you want to create a matrix.

2. Your equations are NOT unit balanced with the given guess values for b2 and D2, set them to be 1 m each to correct that.

3. The root function can solve only ONE variable, not two, and not an expression (like b2/D2)...

In this case you can pull a trick to solve it with root anyway: Multiply the first equation on both sides with D2^2, then the left hand segment becomes equal to the right-hand segment of the second, and we can solve for D2:

Now we know D2, we can solve b2 with:

Or you can look up how to use a solve block in Prime poperly, and use that.

Or you can solve the set symbolically, like I showed in my first reply.

Success!

Luc

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05-11-2021
02:19 PM

05-11-2021
02:19 PM

Re: Help regarding root function or find function

for that equation, i used it like that because i received like that the formula with []. Thank you so much for the help!

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